Daniel Johnson: Our subject is the Left and the Jews. A famous phrase from the 19th century—I think it came from the German social democrat August Bebel—was that "anti-Semitism is the socialism of fools". If that was true then, there are still plenty of these fools around today. Just as in the 19th century, when leading figures of the Left such as Karl Marx set a bad example in their writings about the Jewish people, so today we have a problem on the Left. Where does this come from? Why does it exist? For so many years, the Left, if we define it as beginning with the French Revolution, was seen as the friend of the Jewish people, of emancipation, toleration and equality. But the problem, I think, stems from something which Isaac Deutscher, a great icon of the Left, called the "non-Jewish Jew". The price to be exacted in return for emancipation and full equality was that Jews should give up everything that was distinctive and specifically Jewish. For years, most on the Left did not believe this, but some did. Karl Marx, above all, began the trend towards anti-Semitism on the Left. These leftist thinkers saw thousands of years of Jewish tradition, religion and ritual as in some sense a burden to be sloughed off.

In today's world that attitude still exists, but it has been hugely exacerbated by the unholy alliance that we have found among elements of the Left-not, by any means, among everyone-and the forces of Islamism. A whole new dimension has been created. We began to see this most visibly in the 1960s after the Six-Day War, when anti-Zionism morphed into the "new anti-Semitism", as it has often been called. In this country today, and indeed across the West, anti-Semitism is no longer the preserve of the extreme Right. It has become embedded even in the respectable salons and newspaper offices of the Left.

Nick Cohen: This discussion is like wading into a minefield. Because what do you mean by Left? As Daniel suggested, there are all kinds of shades of opinions on the Left, on this as any other issue. It is like saying, "The Right and the Jews". You can't debate without generalisations—you can't write without generalisations—so it is certainly true that there are anti-Semites on the Left. But it is equally true that left-wing thought can lead to conspiracy theorising. The late 20th century saw the collapse of socialism. From the 1880s through to the 1980s, you would have none of my problems of definition about talking to the Left. If you were left-wing, you were a socialist of some sort. Socialism died before the Berlin Wall came down. All over the world, people were giving up on socialism, not least Communists, especially in China and Russia.

You then have a problem with people who are raging, often with very good reason, against injustice in their society, who call themselves left-wing. What do you do next? How do you explain defeat? One way to explain defeat is a kind of conspiracy theorising. You see this in Britain a lot: people opine on the reasons elections are lost, because of Rupert Murdoch and the Tory press brainwashing the electorate. Lots of people on the Right, for instance, keep saying that the reasons the Tories keep losing elections (and they still haven't won one, incidentally, not even against Gordon Brown. I would have thought that if you missed that goal you might as well give up football completely) is because of the BBC and the liberal media.

It is quite easy to get into conspiratorial ways of thinking. As soon as you start thinking like this, Jews come along, particularly when confronted by an injustice like that suffered by the Palestinians. It is very easy to go from explaining defeat and injustice to saying that there is a Jewish conspiracy which controls British and American foreign policy and runs secret levers of power.

There is one point I would pick out—as I am from the Left—and that I want to emphasise, and I want to do this strongly: you cannot say that it is anti-Semitic to be utterly opposed to the building of settlements on the West Bank, for instance, or to otherwise criticise Israel.

My book You Can't Read This Book deals with censorship, but the greatest fear in Europe for writers and artists ever since Salman Rushdie has been radical Islam. I'm not saying radical Islam has been the only violent force in Europe, but it is the only one which targets writers and artists. I have to take on the notion of Islamophobia, but I can't say it doesn't exist, as there are people who hate Muslims because they are Muslims. There are good reasons for people opposing Islamophobia, but you simply cannot say that publishing a book or writing, or making a work of art, or engaging in legitimate criticism about things like the theocratic regime in Iran is a kind of racism. It's not: it is normal political criticism, and not racist.

Equally with anti-Semitism. You just can't say that people who are appalled by what the Likud government has done are simply racists. You must do a bit better than that. In a funny way, you let real racists off the hook because you let them hide themselves among the crowd.

DJ: Anthony, is there a problem of the Left and the Jews? How does that fit into the history you tell in your book on anti-Semitism in England?

Anthony Julius: Let me return to something that Nick said. He said, since there isn't a Left, there is only a historical memory of the Left. What form does that historical memory take? There's no doubt that until the 1980s socialism spoke principally for a positive project. It was a reconstruction of society, with a certain optimism, and values we associate mainly with the Enlightenment, anti-clerical hostility towards institutions that were thought to be oppressive and benighted.

NC: Absolutely.

AJ: It was a positive project to be a socialist. It was to be committed to something that was about construction, building, substituting something delinquent and infirm with something more elevated, and improving morally and materially the conditions of most people. It would allow most of them to realise themselves, in ways that could only previously have been dreamt of. And that collapsed, in an awfully oppressive sense that there was no alternative to existing arrangements. There was no fundamental alternative to the market economy or mixed economy, no alternative to representative democracy—even though democracy leads to large sections of society being alienated from the political process. We live in an imperfect world. That really cannot be overstated.

There was a disaster in the thinking of the Left, and progressive people in general. The question was, what to do with that disaster? A number of different positions were taken, with a number of different solutions to that problem. First, simple withdrawal into private life—depart from the political field and commit oneself to novel writing or gardening. Plenty of people did that. One comes across people of a certain age—like some us sitting here today—who were firebrands in their twenties. Now they are lawyers or journalists or columnists of one kind or another. Essentially they lead a private life. It is one perfectly honourable solution, albeit a rather depressing one.

There is another option, which is to commit oneself to a form of liberal politics: a new emphasis on human rights, an advocacy of political reform through law reform, championing principles like free speech or free assembly. In other words, they take liberalism and rights seriously, as a very well-known liberal American jurist once said: giving substance to liberalism's promise.

So that's another option. For me, that is the best of the options. There is a third option, which is to associate oneself with local campaigns or objectives, to give up trying to reconstruct society and instead to commit oneself to causes. Green politics, feminism, prisoners' rights, for instance. Not as part of the second project (which is taking liberalism seriously) but rather as a sort of subversive challenge to existing arrangements, leading to who-knows-where. The most important theorist of that kind of post-leftist politics was a Frenchman, Michel Foucault.

And then there's a fourth position, the one which is most problematical for those of us who are Jews or who make common cause with Jews in the fight against anti-Semitism. It is a kind of impure nihilism, a kind of destructive fury or a perpetuation of the antagonisms of the pre-1989 Left, but without any balancing constructive project, so one continues in one's war against America as if the Cold War still existed and the Soviet system still existed. But because there is no real alternative, one is led into more and more extreme gestures of anger and hatred and violence.

I think of the four responses I have identified, the fourth is most difficult for Jews: the searching for enemies-the pursuit of the enemy for its own sake. Jews have comprised the major enemy—certainly the major internal enemy—in the imagination of the West for perhaps 1,500 years. Of course, when that then becomes part of a larger political project, anti-Semitism is not terribly far away.

So in my general overview, of the four options following the collapse of the Left, the fourth is the one I would most identify as problematical. I would say, perhaps, in response to Nick, and building on what he said rather than dissenting from it, a more precise title for the problem we are addressing now is not so much the Jews and the Left but the Jews and the post-Left.